Plant care
Arrow Arumtemperature & humidity
Peltandra virginica
More about arrow arum
Ideal temperature for arrow arum
Aim for -20°C to 32°C (-4°F to 90°F) on the thermostat and you've handled the easy part. The hard part is the half-metre around the plant: window glass that drops to near-freezing on a January night, a radiator pumping out hot dry air, a draught from an opened front door. Move the plant 30 cm and you've usually fixed the problem. Below roughly -20°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Arrow Arum is comparatively hardy (USDA 5-9, RHS H5). Within that range it tolerates a cold dormant spell outdoors; outside it, grow it in a container you can move under cover or overwinter in a cool but frost-free spot. Hardiness assumes an established plant in well-drained soil — a wet, cold root zone kills far more plants than cold air alone.
Humidity for arrow arum
Arrow Arum sits happiest at around High (65–100%) relative humidity. A natural inhabitant of marshes and swamp edges; ambient outdoor humidity in pond-side conditions is usually ideal — no supplemental misting required when grown in the ground. The usual low-humidity tell is crisp brown leaf tips and edges while the soil moisture is fine — a sign the air, not the watering, is the problem. If you need to raise it, the reliable methods are grouping plants together, standing the pot on a tray of damp pebbles (the pot above the waterline, never in it), or running a small humidifier in winter when indoor heating dries the air most. Misting is the least effective — it raises humidity for minutes, not hours.
Arrow Arum temperature & humidity — frequently asked questions
What temperature is best for arrow arum?
Arrow Arum grows best between -20°C to 32°C (-4°F to 90°F). Keep it out of cold draughts, off freezing windowsills in winter, and away from the hot dry air directly above radiators — the extremes matter far more than the average room temperature.
How cold can arrow arum tolerate?
Arrow Arum starts to suffer below roughly -20°C. It tolerates a cold dormant period within USDA 5-9, but a wet cold root zone is more dangerous than cold air.
What humidity does arrow arum need?
Arrow Arum prefers about High (65–100%) relative humidity. A natural inhabitant of marshes and swamp edges; ambient outdoor humidity in pond-side conditions is usually ideal — no supplemental misting required when grown in the ground.
How do I raise humidity for arrow arum?
Group it with other plants, stand the pot on a tray of damp pebbles (kept above the waterline), or run a small humidifier in winter. Misting only helps for a few minutes, so it is the weakest option for a plant that genuinely needs more humidity.
Can arrow arum live outside?
Arrow Arum is rated for USDA zone 5-9 and RHS hardiness H5. Within that range it can stay outdoors; outside it, grow it in a moveable container and protect the roots from a wet, cold winter.
More arrow arum care
In the UK? Keeping arrow arum warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full arrow arum care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.